I'd like to clear up b*****t about gear oil in a M5OD trans.

[90B24wd]

What I'm saying is I liked what the gear oil did to the gears & bearings in my trans.
(mirror smooth surfaces) Probably the gear oil was in your trans so long it turned in to
goo. You didn't say what it looked like when you drained it. Did you ever try mixing thinset (used in setting ceramic tile) when you don't have the right amount water. The drill
that is used to mix it with will take a beating. And thats what I think your drive train was going through. But I'll bet that your trans with the ATF in there is better than new!
I am not putting back gear oil my trans! The gear oil cleaned up the rough spots already. I'll be putting ATF back in there.
I scored 2 more m5od's on my lunch break yesterday at my favorite JY for $25.00 apiece. Also found a m5od-r2 at another site for free.

 

[jhammel85]

I scored 2 more m5od's on my lunch break yesterday at my favorite JY for $25.00 apiece. Also found a m5od-r2 at another site for free.

Thats it?! Lucky man...Do they need to be rebuilt or?

 

[90B24wd]

1 is for 2.9 2wd. Gears looks OK and rotates freely. I think syncro's needs to be replaced. The other is for a 2.3 2wd. 3rd gear & counter gears are in pieces. What I like about this one is it has the upgraded 5th & reverse gears which I will be putting in my 88 trans.

 

[90B24wd]

Okay, you take your finding on one tranny you pulled apart, and I'll give you my rebuttal.

I bought my Mazda with 140k miles, at 170k miles it started vibrating HORRIBLE at 15mph. I'm talking enough vibration where I could mix a drink by setting it on the dash, and you can't see out the rearview mirror as if I had subs. After putting it in the air and getting awfully confused when everything checked out, changing wheel bearings, changing brakes, tearing the rearend apart and replacing rear bearings and brakes - my uncle Ricky suggested we check out the fluid. It was gear oil, no question. So, I put in ATF, and 200 miles later - no more vibration. Truck drives like a new one.

You're another one, you still don't get it do you. The answer is staring at you in your face. You admitted it "Truck drives like a new one". YOU CAN NOT LIE WE READ WHAT YOU WROTE!!! Don't you see your truck got a anama shot of gear oil and now everything is better. Kapish
AS for your vibration, it could of been something else or it could of been related.

 

[Explorin94]

Like I stated in a previous post you are beating a dead horse. For the immaculate internals (as you say) that you found with the inside of your trans may not be the same for someone else.....consider yourself lucky. Cause it wasn't 80w90 gear oil that was in there...there are thinner grades of gear oil that somebody else may have dumped in it. You can talk till you are blue in the face about the gear oil and it won't change a thing....ATF does just the same as what you say the gear oil did. Enough said.

 

[90B24wd]

Like I stated in a previous post you are beating a dead horse. For the immaculate internals (as you say) that you found with the inside of your trans may not be the same for someone else.....consider yourself lucky. Cause it wasn't 80w90 gear oil that was in there...there are thinner grades of gear oil that somebody else may have dumped in it. You can talk till you are blue in the face about the gear oil and it won't change a thing....ATF does just the same as what you say the gear oil did. Enough said.

If ATF can do what gear oil or what ever heavy oil that was in my trans had,
why then do some of these trans whine? (excluding the the loss of fluid)
Both of my running truck & bronco has ATF in them and they are whiners.
I do not know the past history of my truck cause I'm about the 5th owner.
AS for the trans in my Bronco, I rescued it from an abandoned Explorer.
I was thinking to use my Bronco as a guinea pig to prove my case, since
I was planning to replace it with a rebuilt one anyway. (got 3 others to chose from) Being that the trans in my Bronco now is a known whiner and that by replacing the ATF with gear oil I can prove my point. One problem I have is, I don't know how far gone the bearings is in the Bronco's trans. The other is I have posted photo's here before but now my album has vanished.
Picture it this way, when you are cutting plastic filler (bondo) you don't cut
it 220 grit sandpaper = (ATF) first. You cut it with 60 or 80 grit = (heavy oil). I left the rasp out.

 

[gribly]

You're another one, you still don't get it do you. The answer is staring at you in your face. You admitted it "Truck drives like a new one". YOU CAN NOT LIE WE READ WHAT YOU WROTE!!! Don't you see your truck got a anama shot of gear oil and now everything is better. Kapish
AS for your vibration, it could of been something else or it could of been related.

Well, I'd like to ask if you would please not change my story around, it happened to me, not you. I didn't change everything all at once - the fluid was a shot in the dark a few days later, and low and behold, it was gear oil. I changed it out to ATF, and it started getting better. A few hundred miles later it got better. I'll admit it doesn't quite drive like brand new, but it's a damn sight better than when it had gear oil in it. I'm going to rebuild it when I change my clutch, I have to get up to full operating temperature to use 5th without it making my keys jingle.

Not to change your story, either, but how positive are you that the shiny new looking surfaces in your tranny are not shiny due to premature wear from the parts polishing each other down?

 

[Rogue_Wulff]

You can run 90W gear oil in YOUR transmission if you want to, but I'm gonna stick to the recommended lube in mine.

There's an old road racer "trick" of using a 50/50 mix of 90W/ATF in older transmissions that called for 90W. It made the trans last longer, as the 90W didn't get up to temp quickly enough to protect the bearings and other moving parts from getting too hot and wearing prematurely. Some old school racers swear the 50/50 mix would make a trans last 4-5 seasons, and they would be lucky to "only" go thru 2 trans in a single season using the 90W as spec'd by the manufacturer.
I know a lot of guys using the 50/50 mix in older Nissan/Datsun Z cars and Mazda Rotary cars for the street. They swear it makes the trans shift better, and even gives them a mild boost in MPG, compared to when they were using the 90W as originally spec'd. As wild as some of those engines have been built, they need all the help they can get with MPG.....
Personally, I run a 75W-90 synthetic in my RX7 transmission, and I could tell a difference in how it worked almost immediately, compared to the 90W I drained out. I also run the same stuff in the diff, with the LSD additive.

About the heaviest lube I would ever consider putting in a Ranger/B-series M5OD would be 10W 30 motor oil. I've heard of many guys doing that in the F150 variation of this trans, as well as the heavier ZF5 found in F250 and heavier trucks, all with good service.
90W is just too heavy. In cold weather, you'll be lucky to get the trans to even shift.
Of course, seeing as to how you claim to be in hawaii, you don't have a clue what cold weather is, while those of us who live on the biggest island of the US know all too well what cold weather is, and how it can effect a vehicle.......

 

[modelageek]

As I am cleaning up a 2.9 M5OD tonight getting it ready for a rebuild, I have noticed that this trans is in very mint condition internally. And why I say this is because while I was cleaning the bearings with solvent, it spins quietly & smooth (even when dry). What I got here is a well broken in trans!!!
I don't remember what the mileage of the truck but, it was an 88 2wd bought 7-8 years ago for parts. (payed $75.00 for it) The outside was caked with grime. This trans is the in best condition compared to the other 4 that I tore apart this week. Some of the others were screwed up rebuilds. The machined & bearing surfaces looks like a mirror. Even the syncros is in mint condition.
I do not know how long the gear oil was in there but thank you to the person who put it in.
The bad part is where the syncros mates to the gears, it is shiny and smooth. This can be corrected with 80 grit sandpaper. The only reason why I think that gear oil should not be used is because where the syncros meshes with the cone part of the gears, it becomes to smooth not letting the syncros to bite the cone for smooth shifting.
I do not have to change any bearings. I'll only change the output shaft & seals.
Gear oil is good for gears & bearings but not for smooth shifting.
I would like to try a trans oil made by Specialty Formlations but don't know where to get it from.
So for those who have gear oil in their M5OD trans it is not all that bad. And it is not because this trans has close tolerances ATF must be used either.

I run ATF in my Crankcase and I run 5w30 motor oil in my M5OD........what do those engineers know anyways.......it purs like a kitten

 

[90B24wd]

Not to change your story, either, but how positive are you that the shiny new looking surfaces in your tranny are not shiny due to premature wear from the parts polishing each other down?[/QUOTE]

You got a point there. Well I assumed that compared to the other 4 M5OD's
that I torn apart, that the machined & bearing surfaces had a satin finish much finer than brushed stainless and their fore did not break in as well as the
trans with the "heavier oil". (I will not use the other tabooed words) The syncro's had a lot tooth still. (it was compared with a new one side by side).
I went through my collection of M5OD's and found another trans that also has that "heavier oil" in it. I can smell it. It too has shiny surfaces and not that satin look. The syncro's looks worn down in this one. I guess it depends how long that "heavier oil" has been there.
I have since won a bid on a book "How to rebuild & modify your manual trans"
so I can educate myself more on this subject and not make an ass of myself.

 

[84bluebronco2]

When I change the ATF in my M5OD, I'm going to put ATF in it. I believe Ford says use ATF. Ford might not be able to make an automatic, but they did something special with my M5OD.

 

[gribly]

When I change the ATF in my M5OD, I'm going to put ATF in it. I believe Ford says use ATF. Ford might not be able to make an automatic, but they did something special with my M5OD.

It's not a Ford tranny, it's actually designed by Mazda.

 

[Rogue_Wulff]

When I change the ATF in my M5OD, I'm going to put ATF in it. I believe Ford says use ATF. Ford might not be able to make an automatic, but they did something special with my M5OD.

Ford quit making "Real" automatic transmissions when they dropped the C6. THAT was a transmission.....

As pointed out, the M5OD is Mazda's doing. In fact, it's about the only
part they supplied for my "Mazda" B2300.......

 

[BuiltFordTough12]

ATF worked great in my old 1998 m5od. I changed it every 30-45k and It had about 175k never being rebuilt when I sold it. I also happen to know that it is still a daily driver!!

 

[90B24wd]

Remember that $25.00 2.9 2wd trans I bought on my lunch break. Well I split that one open today and it also had that "heavy oil" in it. I'm taking alot of pics to post it here
when I figure how to do it. The inner walls of the trans is dark gooie green. The magnetic drain plug has a greasy goo on it. There is no grainy metal pieces like the trans with ATF in them. It smells, but not that bad cause its dried up. This is the 3rd trans out of 12 that I found with "heavy oil" in it!!!
And also the machined & bearing surfaces looks like hard chrome on a hydraulic ram. The syncro's looks ok, just need to check them with a feeler gauge.

I helped a friend this weekend rebuild his 3.0 trans that had a hard time going into 3rd.
There was a chip & crack on third gear. All the syncros were changed. The guts from this trans came out of a 4.0. I'm short of 4.0 3rd gear myself, so I just swap a lower ratio set back in.